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I. F. FOWLER 81? M. V. B. WALDORF. GOILBD SPRING.

No. 380,651. Patented Apr. 3, 1888.

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UNITED STATES PATENT OFFICE.

FORMAN F. FOWLER AND MARTIN V. B. WALDORF, OF WOLCOTT, NEW YORK.

COILED SPRING.

SPECIFICATION forming part of Letters Patent No. 380,651, dated April 3, 1888.

Application filed January 19, 1887. Serial No. 224,824. (No model.)

To all whom/it may concern:

Be it known that we, FORMAN F. FOWLER and MARTIN V. B. WALDORF, citizens of the United States, and residents of W'olcott, in the county of WVayne and State of New York, have invented certain new and useful Improvements in Springs; and we do declare the following to be afull, clear, and exact description of the invention, such as will enable others skilled in the art to which it 'appertains to make and use the same, reference being bad to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

Figure l of the drawings is a representation of a plan view. Fig. 2 is a side elevation. Fig. 3 isa detail View of a portion of the wire, showing the construction of the smaller end of the spring.

The aim of this invention is to provide a coiled spring which will offer a uniform or practicallyuniform resistance notwithstanding variations in its length by compression or expansion; and to this end it consists, first, in the form of a spiral or helical spring or bar of diminishing diameter from the smaller to the larger end of the spring, and, second, in a spring having its successive coils or convolutions brought nearer together as they approach the smaller end of the spring.

Referring by letter to the accompanying drawings, A designates the spring, which is of the usual helical or conical form, consisting of a continuous wire commencing at the base and winding inward and upward in substantially the ordinary manner. This wire, instead of being made of uniform size or diameter from one end to the other, as usual, is constructed of a gradually-diminishing diameter from the larger end,b, of the spring toward the smaller end ,a. It is preferred to have this taper continue throughout the entire length of the wire, or so much of the same as is embraced in the spring proper; but the taper may cease at a short distance from the end, if preferred. Instead of coiling the wire, as usual,

at a uniform pitch or inclination, so that the successive coils or convolutions are separated vertically to the same extent, we gradually diminish the pitch from the larger toward the smaller end, so that the successive convolutions or coils are brought closer together as the top of the spring is approached.

In practice we find that a spring thus constructed is far superior to those of ordinary form as regards the ease and smoothness of its action.

The extreme ends of the wire may be fashioned into any appropriate form to admit of their being pushed to place in their bearings.

We prefer to construct the spring of steel wire; but it may be composed of brass or other suit-able material, and may be made of such size and form as will be best adapted to the particular objects to which. they are to be applied.

Springs possessing the peculiarities herein described will be found serviceable in wagons, railway-car trucks, spring-beds, and generally in all places in which coiled springs are demanded.

An esssential feature of the invention is the finish or small end of the spring. It will be seen that by drawing the steel or other material down to a fiat taper or wedge shape it can be coiled closer to form an eye for bolt or rivet to connect a plate or other attachment to the spring. Consequently by making the bar of which the spring is made with a fiat taper or wedge shape, and forming an eye at the small end of this and all helical and conical shaped springs adds] more strength to the spring by bringing the convolutions closer and smaller.

By making an eye, a, in the small end of the spring we form a fastening device of the spring itself.

As the coils get smaller in diameter they necessarily have more stiffness or tension that is, it requires a greater force to bend them than the larger coils. The main stress of the load consequently falls on the larger coils, which are thus rendered liable to break. To prevent this, as the coils decrease in diameter their pitch is lessened and the stiff-' ness or tension of the spring is made equable throughout.

Having described this invention, what we claim, and desire to secure by Letters Patent, 1s- 7 The herein-described coiled spring, made of I In testimony whereof we affix our signatures a cylindrical rod decreasing in diameter to- 1 in presence of two witnesses. ward the apex of the spring, and at the apex I FORMAN F. FOWLER. squared and coiled into an eye the coils of the MARTIN V. B. VVALDORF. 5 spring decreasing in diameter and in pitch Viitnesses:

from the base to the apex, substantially as S. M. WAITE, specified. l J. NV. HINMAN. 

